Broadcast router configured for alternately receiving multiple or redundant reference inputs

ABSTRACT

A broadcast router includes a router matrix having input and output sides. Coupled to the input side of the router matrix are first and second reference inputs. The first reference input is configured for application of a first reference signal thereto while the second reference input is configured for selective application of either a second reference signal or a redundancy of the first reference signal thereto. The broadcast router further includes N inputs, M outputs and a routing engine, coupled between the N inputs and the M outputs, for applying selected ones of the N inputs to the M outputs. A reference select circuit is coupled between the first and second reference inputs and the routing engine.

CROSS REFERENCE

This application is related to U.S. Provisional Patent Application Ser.No. 60/390,742 filed Jun. 21, 2002.

This application is also related to co-pending U.S. Patent ApplicationSer. Nos. PCT/______ (Atty. Docket No. IU010620), PCT/______ (Atty.Docket No. IU020157), PCT/______ (Atty. Docket No. IU020158), PCT/______(Atty. Docket No. IU020159), PCT/______ (Atty. Docket No. IU020160),PCT/______ (Atty. Docket No. IU020162), PCT/______ (Atty. Docket No.IU020252), PCT/______ (Atty. Docket No. IU020253), PCT/______ (Atty.Docket No. IU020254), PCT/______ (Atty. Docket No. IU020255), andPCT/______ (Atty. Docket No. IU020256), all of which are assigned to theAssignee of the present application and hereby incorporated by referenceas if reproduced in their entirety.

FIELD OF THE INVENTION

The present invention relates to broadcast routers and, moreparticularly, to a broadcast router configured for alternately receivingmultiple or redundant reference inputs at an input side thereof.

BACKGROUND OF THE INVENTION

A broadcast router allows each one of a plurality of audio outputstherefrom to be assigned the signal from any one of a plurality of audioinputs thereto. For example, an N×M broadcast router has N audio inputsand M audio outputs coupled together by a router matrix which allows anyone of the N audio inputs to be applied to each one of the M audiooutputs. In addition, a broadcast router requires at least one referenceinput. A variety of reference signals which may be applied to areference input are known. They include, among others, a video blackreference signal, a tri-level synchronization signal and a digital audioreference signal (“DARS”). Reference signals such as these may be usedby the broadcast router for a variety of purposes. Oftentimes, areference signal is used to time switches within the broadcast router. Abroadcast router may also use a reference signal for synchronizationpurposes. For example, a broadcast router may retime its audio outputsto be closer to the reference signal than to the audio inputs. Priorbroadcast routers used phased lock loop techniques to continually alignits audio outputs to the incoming reference signal. Since an attempt tosynchronized a non-synchronous signal will damage the signal, suchbroadcast routers also required the use of a sync/non-sync detectioncircuit which determined whether the output audio signal should besynchronized.

Broadcast routers having multiple reference inputs are known in the art.In the past, however, multiple reference inputs have been predefined aseither redundant or independent. If the multiple reference inputs wereredundant to one another, the same reference signal would be supplied toeach reference input. Conversely, if the multiple reference inputs wereindependent of one another, a different reference signal would besupplied to each reference input. Once predefined as either redundant orindependent, the multiple reference inputs could not be used as theother unless the broadcast router was physically modified in somefashion, for example, by actuating a physical switch or selecting asetting using a graphical user interface (“GUI”).

SUMMARY OF THE INVENTION

A broadcast router includes a first reference input, a second referenceinput, a reference select circuit coupled to the first and secondreference inputs and at least one router component coupled to thereference select circuit. The reference select circuit is configured to:(1) pass a first signal applied to the first reference input to the atleast one router component as a first reference signal and pass a secondsignal applied to the second reference input to the at least one routercomponent as a second reference signal upon determining that the firstand second signals are error-free; (2) pass the first signal to the atleast one router component as the first reference signal and as thesecond reference signal upon determining that the first signal iserror-free and the second signal is not error-free; and (3) pass thesecond signal to the at least one router component as the firstreference signal and as the second reference signal upon determiningthat the first signal is not error-free and the second signal iserror-free.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a fully redundant linearly expandablebroadcast router constructed in accordance with the teachings of thepresent invention;

FIG. 2 is an expanded block diagram of a router matrix of the broadcastrouter of FIG. 1; and

FIG. 3 is a flow chart of a method of selectively providing multiple orredundant reference inputs to the broadcast router of FIG. 1.

DETAILED DESCRIPTION

Referring first to FIG. 1, a broadcast router 100 which has beenconfigured for alternately receiving multiple or redundant referenceinputs in accordance with the teachings of the present invention willnow be described in greater detail. As disclosed herein, the broadcastrouter 100 is a fully redundant linearly expandable broadcast router. Itshould be clearly understood, however, that it is fully contemplatedthat other types of broadcast routers besides the specific type ofbroadcast router disclosed herein may be configured for alternatelyreceiving multiple or redundant reference inputs as well. As may now beseen, the fully redundant linearly expandable broadcast router 100 iscomprised of plural broadcast router components coupled to one anotherto form the larger fully redundant linearly expandable broadcast router100. Each broadcast router component is a discrete router device whichincludes first and second router matrices, the second router matrixbeing redundant of the first router matrix. Thus, each broadcast routerhas first and second routing engines, one for each of the first andsecond router matrices, each receiving, at an input side thereof, thesame input digital audio streams and placing, at an output side thereof,the same output digital audio streams. As disclosed herein, each of thebroadcast router components used to construct the fully redundantlinearly expandable broadcast router are N×M sized broadcast routers.However, it is fully contemplated that the fully redundant linearlyexpandable broadcast router 100 could instead be constructed ofbroadcast router components of different sizes relative to one another.

As further disclosed herein, the fully redundant linearly expandablebroadcast router 100 is formed by coupling together first, second, thirdand fourth broadcast router components 102, 104, 106 and 108. Of course,the present disclosure of the fully redundant linearly expandablebroadcast router 100 as being formed of four broadcast router componentsis purely by way of example. Accordingly, it should be clearlyunderstood that a fully redundant linearly expandable broadcast routerconstructed in accordance with the teachings of the present inventionmay be formed using various other numbers of broadcast router componentsas long as the total number of broadcast router components whichcollectively form the linearly expandable broadcast router is equal toor greater than three. The first, second, third and fourth broadcastrouter components 102, 104, 106 and 108 which, when fully connected inthe manner disclosed herein, collectively form the fully redundantlinearly expandable broadcast router 100, may either be housed togetherin a common chassis as illustrated in FIG. 1 or, if desired, housed inseparate chassis. While, as previously set forth, the broadcast routercomponents 102, 104, 106 and 108 may have different sizes relative toone another or, in the alternative, may all have the same N×M size, onesize that has proven suitable for the uses contemplated herein is256×256. Furthermore, a suitable configuration for the fully redundantlinear expandable broadcast router 100 would be to couple five broadcastrouter components, each sized at 256×256, thereby resulting in a1,280×1,280 broadcast router.

The first broadcast router component 102 is comprised of a first routermatrix 102 a and a second (or redundant) router matrix 102 b used toreplace the first router matrix 102 a in the event of a failure thereof.Similarly, each one of the second, third and fourth broadcast routercomponents 104, 106, and 108 of the fully redundant linearly expandablebroadcast router 100 are comprised of a first router matrix 104 a, 106 aand 108 a, respectively, and a second (or redundant) router matrix 104b, 106 b and 108 b, respectively, used to replace the first routermatrix 104 a, 106 a and 108 a, respectively, in the event of a failurethereof. Of course, the designation of the second router matrices 102 b,104 b, 106 b and 108 b as backups for the first router matrices 102 a,104 a, 106 a and 108 a, respectively, is purely arbitrary and it isfully contemplated that any either of a router matrix pair residingwithin a broadcast router component may act as a backup for the other ofthe router matrix pair residing within that broadcast router component.

As may be further seen in FIG. 1, the first router matrix 102 a of thefirst broadcast router component 102, the first router matrix 104 a ofthe second broadcast router component 104, the first router matrix 106 aof the third broadcast router component 106 and the first router matrix108 a of the fourth broadcast router component 108 are coupled togetherin a first arrangement of router matrices which conforms to a fullyconnected topology. Similarly, the second router matrix 102 b of thefirst broadcast router component 102, the second router matrix 104 b ofthe second broadcast router component 104, the second router matrix 106b of the third broadcast router component 106 and the second routermatrix 108 b of the fourth broadcast router component 108 are coupledtogether in a second arrangement which, like the first arrangement,conforms to a fully connected topology. In a fully connected topology,each router matrix of an arrangement of router matrices is coupled, by adiscrete link, to each and every other router matrix forming part of thearrangement of router matrices.

Thus, for the first arrangement of router matrices, first, second andthird bi-directional links 110, 112 and 114 couples the first routermatrix 102 a of the first broadcast router component 102 to the firstrouter matrix 104 a of the second broadcast router component 104, thefirst router matrix 106 a of the third broadcast router component 106and the first router matrix 108 a of the fourth broadcast routercomponent 108, respectively. Additionally, fourth and fifthbi-directional links 116 and 118 couple the first router matrix 104 a ofthe second broadcast router component 104 to the first router matrix 106a of the third broadcast router component 106 and the first routermatrix 108 a of the fourth broadcast router component 108, respectively.Finally, a sixth bi-directional link 120 couples the first router matrix106 a of the third broadcast router component 106 to the first routermatrix 108 a of the fourth broadcast router component 108. Variously,the bidirectional links 110 through 120 may be formed of copper wire,optical fiber or another transmission medium deemed suitable for theexchange of digital signals.

Similarly, for the second arrangement of router matrices, first, secondand third bi-directional links 122, 124 and 126 couples the secondrouter matrix 102 b of the first broadcast router component 102 to thesecond router matrix 104 b of the second broadcast router component 104,the second router matrix 106 b of the third broadcast router component106 and the second router matrix 108 b of the fourth broadcast routercomponent 108, respectively. Additionally, fourth and fifthbi-directional links 128 and 130 couple the second router matrix 104 bof the second broadcast router component 104 to the second router matrix106 b of the third broadcast router component 106 and the second routermatrix 108 b of the fourth broadcast router component 108, respectively.Finally, a sixth bi-directional link 132 couples the second routermatrix 106 b of the third broadcast router component 106 to the secondrouter matrix 108 b of the fourth broadcast router component 108. Again,the bi-directional links 122 through 132 may be formed of copper wire,optical fiber or another transmission medium deemed suitable for theexchange of digital signals. Of course, rather than the singlebi-directional links between pairs of router matrices illustrated inFIG. 1, in an alternate embodiment of the invention, it is contemplatedthat the pairs of router matrices may instead be coupled together byfirst and second unidirectional links. Such an alternate configurationis illustrated in FIG. 2.

Referring next to FIG. 2, the first router matrix 102 a of the firstbroadcast router component 102 will now be described in greater detail.As may now be seen, the first router matrix 102 a of the first broadcastrouter component 102 is comprised of a routing engine 134, a transmitexpansion port 136, a first receive expansion port 138, a second receiveexpansion port 140, a third receive expansion port 142 and a referenceselect circuit 144. By the term “transmit” expansion port, it isintended to refer to an expansion port from which data is transmitted toa selected destination. Similarly, by the term “receive” expansion port,it is intended to refer to an expansion port which receives data from adestination. Residing within the routing engine 134 is switching means(not shown) for assigning any one of plural input digital audio datasignals received as inputs to the routing engine 134 to any one ofplural output lines of the routing engine 134. Variously, it iscontemplated that the routing engine 134 may be embodied in software,for example, as a series of instructions; hardware, for example, as aseries of logic circuits; or a combination thereof. In a broad sense,the transmit expansion port 136 of the first router matrix 102 a of thefirst broadcast router component 102 is comprised of a memory subsystem(not shown) in which plural input digital audio data streams may bebuffered before transfer to their final destinations and a processorsubsystem (also not shown) for controlling the transfer of the pluralinput digital audio data streams received by the transmit expansion port136 to a receive expansion port of the first router matrix of anotherbroadcast router component. Conversely, each one of the first, secondand third receive expansion ports 138, 140 and 142 of the first routermatrix 102 a are, in a broad sense, comprised of a memory subsystem (notshown) in which plural input digital audio data streams received from atransmit expansion port of a first router matrix of another broadcastrouter component may be buffered before transfer to their finaldestination and a processor subsystem (also not shown) for controllingthe transfer of the input digital audio data streams received from thereceive expansion port of the first router matrix of the other broadcastrouter component to inputs of the routing engine 134.

The router matrix 102 a includes an input side 102 a-1 equipped with oneor more data inputs 143 and an output side 102 a-2 equipped with one ormore data outputs 149. N input digital audio data streams are receivedby the one or more data inputs 143 and transported to the routing engine134 and the transmit expansion port 136. It is contemplated that therouter matrix 102 a shall conform to either the Audio EngineeringSociety-3 (or “AES-3”) standard or the multichannel digital audiointerface (or “MADI”) standard set forth in the AES-10 standard. In thisregard, it should be noted that a MADI input digital audio data streammay contain up to 32 AES-3 digital audio data streams. Accordingly, ifthe AES-3 standard is used, the router matrix 102 a will require Ninputs 143 to receive the N digital audio data streams to be transportedto the routing engine 134 and the transmit expansion port 136.Conversely, if the MADI standard is used, the router matrix 102 a willneed only N/32 inputs 143 to receive the N digital audio data streams tobe transported to the routing engine 134 and the transmit expansion port136. Of course, extraction circuitry (not shown), within the routermatrix 102 a, would be needed to extract the N AES-3 input digital audiodata streams from the MADI input digital audio data stream. Of course,it should be readily appreciated that other types of input data streamsother than the input digital audio streams disclosed herein are equallysuitable for use with the first router matrix 102 a of the firstbroadcast router component 102. For example, it is contemplated that thefirst router matrix 102 a of the first broadcast router component 102may instead be used with other low bandwidth digital signals such ascompressed video and data signals. It is further contemplated that, withminor modifications, for example, faster hardware, the first routermatrix 102 a of the first broadcast router component 102 may be usedwith non-compressed digital video signals.

Input digital audio data streams 1 through N are fed into the routingengine 134 and the transmit expansion port 136 of the first routermatrix 102 a of the first broadcast router component 102. From thetransmit expansion port 136, input digital audio data streams 1 throughN are forwarded to a receive expansion port (not shown) of the firstrouter matrix 104 a of the second broadcast router component 104 overthe link 110, a receive expansion port (also not shown) of the firstrouter matrix 106 a of the third broadcast router component 106 over thelink 112 and a receive expansion port (also not shown) of the fourthrouter matrix 108 a of the fourth broadcast router component 108 overthe link 114. In turn, input digital audio data streams N+1 through 2Nare transmitted, by a transmit expansion port (not shown) of the firstrouter matrix 104 a of the second broadcast router component 104, to thefirst receive expansion port 138 over the link 110, input digital audiodata streams 2N+1 through 3N are transmitted, by a transmit expansionport (also not shown) of the first router matrix 106 a of the thirdbroadcast router component 106, to the second receive expansion port 140over the link 112 and input digital audio data streams 3N+1 through 4Nare transmitted, by a transmit expansion port (also not shown) of thefirst router matrix 108 a of the fourth broadcast router components 108,to the third receive expansion port 142 over the link 114. Finally,input digital audio data streams N+1 through 2N are fed into the routingengine 134 by the first receive expansion port 138, input digital audiodata streams 2N+1 through 3N are fed into the routing engine 134 by thesecond receive expansion port 140 and input digital audio data streams3N+1 through 4N are fed into the routing engine 134 by the third receiveexpansion port 142.

The router matrix 102 a utilizes a non-traditional approach to thesynchronization of input and/or output signals. More specifically,rather than continually aligning the input and/or output signals to areference signal, the router matrix 102 a will align a signal with thereference signal only once. If the signal to be aligned is a synchronoussignal, it will stay aligned. Conversely, if the signal to be aligned isnot a synchronous signal, while it won't stay aligned, it will not bedamaged in any way. Because synchronization is achieved using a singlealignment with the reference signal, the router matrix 102 a performsthe same with a correct reference signal, an incorrect reference signalor a missing reference signal. Of course, there are a number ofconditions, including acquiring a new input signal, switching to adifferent input signal and acquiring a new reference signal, which willcause the router matrix to subsequently perform another re-alignmentwith the reference signal.

Turning to FIG. 2, therefore, the configuration of the router matrix 102a will allows for the selective receipt of multiple or redundant inputswill now be described in greater detail.

As may now be seen, the router matrix 102 a further includes a firstreference input 146 and a second reference input 148. As previously setforth, the first and second reference inputs 146 and 148 may be used,depending on user preference, to provide a redundant reference input ormultiple reference inputs to the router matrix 102 a If the user prefersthat the second reference input 148 be used to provide a redundantreference input to the router matrix 102 a, REF A, the signal applied tothe first reference input 146 by the user would be generally identicalto REF B, the signal applied by the user to the second reference input148. While generally identical, however, to ensure the availability ofREF B in the event that REF A is lost, it is preferred that REF A andREF B are supplied by discrete signal sources. Conversely, if the userprefers that the first and second reference inputs 146 and 148 are usedto provide multiple reference inputs to the router matrix 102 a,reference signal REF A would be different from reference signal REF B.For example, REF A may have a frequency of 60 MHz while REF B may have afrequency of 50 MHz.

The reference signals REF A and REF B applied to first and second inputs146 and 148, respectively, are fed into the reference select circuit144. In turn, the reference select circuit 144 propagates correspondingreference signals REF A′ and REF B′ for use by one or more referencesignal-demanding components of the router matrix 102 a. As illustratedin FIG. 2, each one of the reference signals REF A′ and REF B′ outputthe reference select circuit 144 are transferred to the routing engine134 and the transmit expansion port 136. It should be noted, however,that it is fully contemplated that each one of the reference signals REFA′ and REF B′ output the reference select circuit 134 are alsotransferred to each one of the first, second and third receive expansionports 138, 140 and 142 but that the interconnections necessary to showsuch transfers were omitted from FIG. 2 to maintain clarity of thedrawing. It should also be clearly understood that it is furthercontemplated that the aforementioned reference signals may also bepropagated to any number of other components of the router matrix 102 awhich were omitted from FIG. 2 for ease of description. Finally, itshould be understood that the foregoing disclosure of the router matrix102 a as having first and second reference inputs 146 and 148 to whichfirst and second reference signals are applied is purely by way ofexample and it is fully contemplated that the router matrix 102 a may,if desired, have any number of additional reference inputs to whichadditional discrete reference signals and/or additional redundantreference signals may be applied.

Referring next to FIG. 3, the method by which the reference selectcircuit 144 determines which signals to be output as reference signalsREF A′ and REF B′ will now be described in greater detail. The methodcommences at step 150 and, at step 152, the reference select circuitdetect circuit 144 determines if the reference signal REF A is“error-free”. As disclosed herein, the term “error-free” is herebydefined as indicating that the reference signal is present and “locked”.In turn, the term “locked” is hereby defined as indicating that thefrequency of the reference signal is relatively constant. If thereference signal REF A is error-free, the method continues on to step154 where the reference select circuit 144 determines if the referencesignal REF B is error-free. If the reference select circuit 144determines that the reference signal REF B is also error-free, themethod proceeds to step 156 where the reference select circuit 144 setsthe reference signal REF A′ to the reference signal REF A and thereference signal REF B′ to the reference signal REF B. Having selectedthe reference signals to be used as the reference signals REF A′ and REFB′, the method would then end at step 158.

Returning to step 154, if, however, the reference select circuit 144determines that the reference signal REF B is not error-free, i.e., theREF B signal is either absent or the frequency is changing excessively,the method will instead proceed to step 160 where the reference selectcircuit 144 sets the reference signal REF A′ to the reference signal REFA and sets the reference signal REF B′ to the reference signal REF A.Again, having selected the reference signals to be used as the referencesignals REF A′ and REF B′, the method would then end at step 158.

Returning to step 152, if, however, the reference select circuit 144determines that the reference signal REF A is not error-free, i.e., theREF A signal is either absent or the frequency is changing excessively,the method will instead proceed to step 162. At step 162, the referenceselect circuit 144 will determine if the reference signal REF B ispresent. If it is determined that the reference signal REF B iserror-free, the method will continue on to step 164 where the referenceselect circuit 144 sets the reference signal REF A′ to the referencesignal REF B and sets the reference signal REF B′ to the referencesignal REF B. Again, having selected the reference signals to be used asthe reference signals REF A′ and REF B′, the method would then end atstep 158. If, however, the reference select circuit 144 determines, atstep 162, that the reference signal REF B is not present, the methodwill proceed to step 166 where the reference select circuit 144 will setthe reference signals REF A′ and REF B′ based upon a set of pre-selecteddefault criteria. It is contemplated that a variety of default criteriamay be used. For example, one pre-selected set of default criteria maybe that, in the absence of either the reference signal REF A or thereference signal REF B, the reference select circuit 144 may generate a60 MHz signal for output as the reference signal REF A′ and thereference select circuit 144 may generate a 50 MHz signal for output asthe reference signal REF B′. Alternately, the reference select circuit144 may be configured such that, in the absence of either the referencesignal REF A or the reference signal REF B, the reference select circuit144 may decline to provide either the reference signal REF A′ or thereference signal B′. In such a configuration, the components of therouter matrix 102 a which receive the reference signal A′ and/or thereference signal B′ from the reference select circuit 144 should beconfigured for operation in the absence of such reference signals.

It is noted that, in accordance with the method set forth above, thereference select circuit 144 will periodically transmit one referencesignal, for example, REF A, in place of another reference signal, forexample, REF B. However, because the router matrix 102 a synchronizes asignal with the reference signal only once, that signal will not bedamaged in the event that a non-identical reference signal is used inplace of a missing or bad reference signal.

Furthermore, by configuring the first broadcast router component 102 ato include the first reference input 146, the second reference input 148and the reference select circuit 144, a broadcast router which may beselectively operated with multiple or redundant reference signals hasbeen achieved. If a user desires to operate the first broadcast routercomponent 102 a with redundant reference inputs, the user need only tohook copies of the same signal to both the first reference input 146 andthe second reference input 148. Conversely, if a user desires to operatethe first broadcast router component 102 a with multiple independentreferences, the user need only to hook a copy of the first signal to thefirst reference input 146 and hook a copy of the second signal to thesecond reference input 148. No further setup and/or modification by theuser is required for selecting between these alternate modes ofoperation.

Thus, there has been disclosed and illustrated herein a broadcast routerconfigured for alternately receiving multiple or redundant referenceinputs. Of course, while preferred embodiments of this invention havebeen shown and described herein, various modifications and other changescan be made by one skilled in the art to which the invention pertainswithout departing from the spirit or teaching of this invention.Accordingly, the scope of protection is not limited to the embodimentsdescribed herein, but is only limited by the claims that follow.

1. A broadcast router, comprising: a first reference input; a secondreference input; a reference select circuit coupled to said first andsecond reference inputs; and at least one router component coupled tosaid reference select circuit; wherein said reference select circuit:(1) passes a first signal applied to said first reference input to saidat least one router component as a first reference signal and a secondsignal applied to said second reference input to said at least onerouter component as a second reference signal upon determining that saidfirst and second signals are error-free; (2) passes said first signal tosaid at least one router component as said first reference signal and assaid second reference signal upon determining that said first signal iserror-free and said second signal is not error-free; and (3) passes saidsecond signal to said at least one router component as said firstreference signal and as said second reference signal upon determiningthat said first signal is not error-free and said second signal iserror-free.
 2. The apparatus of claim 1, wherein said at least onerouter component further comprises a router matrix.
 3. The apparatus ofclaim 1, wherein said at least one router component further comprises atransmit expansion port.
 4. The apparatus of claim 1, wherein said atleast one router component further comprises at least one receiveexpansion port.
 5. A broadcast router, comprising: a router matrixhaving an input side and an output side; N data inputs coupled to saidinput side of said router matrix, each one of said N data inputsconfigured for providing an input data stream to said router matrix; Mdata outputs coupled to said output side of said router matrix, each oneof said M data outputs configured for providing an output data streamfrom said router matrix; a first reference input coupled to said inputside of said router matrix said first reference input configured forapplication of a first reference signal thereto; and a second referenceinput coupled to said input side of said router matrix, said secondreference input configured for selective application of either a secondreference signal or a redundancy of said first reference signal thereto.6. The apparatus of claim 5, wherein said broadcast router furthercomprises a routing engine coupled between said N data inputs and said Mdata outputs, said routing engine configured to apply selected ones ofsaid N data inputs to said M data outputs.
 7. The apparatus of claim 6,wherein said broadcast router further comprises a reference selectcircuit coupled between said first and second reference inputs and saidrouting engine, said reference select circuit configured to pass a firstsignal applied to said first reference input to said routing engine as afirst reference signal and a second signal applied to said secondreference input to said routing engine as a second reference signal upondetermining that said first and second signals are error-free; (2) passsaid first signal to said routing engine as said first reference signaland as said second reference signal upon determining that said firstsignal is error-free and said second signal is not error-free; and (3)pass said second signal to said routing engine as said first referencesignal and as said second reference signal upon determining that saidfirst signal is not error-free and said second signal is error-free. 8.A method for selectively providing multiple or redundant referenceinputs to a broadcast router, comprising: providing a broadcast routerhaving first and second reference inputs; applying a first referencesignal to said first reference input; if a user desires that saidbroadcast router operate with redundant reference signals, applying saidfirst reference signal to said second reference input; and if said userdesires that said broadcast router operate with multiple referencesignals, applying a second reference signal to said second referenceinput.
 9. The method of claim 8, and further comprising: providing abroadcast router having a reference select circuit to which said firstand second reference inputs are fed, said reference select circuitconfigured to pass signals applied to said first reference input toreference signal-demanding components of said broadcast router as afirst reference signal and signals applied to said second referenceinput to said reference signal-demanding components of said broadcastrouter as a second reference input upon determining that said signalsapplied to said first and second reference inputs are error-free; (2)pass signals applied to said first reference input to said referencesignal-demanding components of said broadcast router as said firstreference input and as said second reference input upon determining thatsignals applied to said first reference input are error-free but signalsapplied to said second reference input are not error-free; and (3) passsignals applied to said second reference input to said referencesignal-demanding components of said broadcast router as said firstreference input and as said second reference input upon determining thatsignals applied to said first reference input are not error-free butsignals applied to said second reference input are error free.
 10. Themethod of claim 9, wherein said reference signal-demanding componentsare reference signal-insensitive.